The voltage of the secondary of the transformer tends to change in a larger range to satisfy the demands for the wide voltage output for the current transformer. For the transformers with an auxiliary winding, since the voltage outputted by the auxiliary winding is proportional to the voltage of the secondary winding of the transformer and as the voltage outputted by the transformer is lower, the voltage coupled on the auxiliary winding is also lower and the voltage outputted by the auxiliary winding is lower. Generally, the auxiliary winding supplies power to the chip via the auxiliary winding circuit. The auxiliary winding circuit generally comprises semiconductor components, such as a diode and a triode. As the voltage outputted by the auxiliary winding circuit is lower, the supply voltage of the chip is lower. The larger supply voltage of the chip will cause damage to the chip. Therefore, for avoiding the damage to the chip as the output voltage of the transformer is lower, a voltage stabilization diode is usually added in the auxiliary winding circuit for ensuring that the input voltage of the chip is not lower than the voltage of the voltage stabilization diode (for instance, the voltage stabilization value of the voltage stabilization diode is set to be 15V). However, after the voltage stabilization diode is configured and once the voltage outputted by the secondary winding of the transformer gets high, the voltage outputted by the corresponding auxiliary winding will rise and the input voltage of the auxiliary winding circuit will rise. With the configuration of the voltage stabilization diode, the output voltage of the auxiliary winding circuit is still maintained at the voltage of the voltage stabilization diode. The voltage drop between the input voltage and the output voltage of the auxiliary winding circuit increases. The voltage drop on the component (such as semiconductor components, such as a diode and a triode) in the auxiliary winding circuit will also increase correspondingly to result in the increase of the idling power consumption.